In the space of one decade, abnormal weather patterns in Arctic Russia have resulted in the death of 80,000 reindeer due to starvation. What's even more shocking is the speed with which it happened: 20,000 deer died in 2006 and 61,000 animals starved to death in 2013. In total, that's 22 percent of the whole reindeer population in the Yamal peninsula.

A study published in Biology Letters now shows that both of those years had a common factor: they experienced the same strange weather pattern at the beginning of November. Researchers are now very worried that the same thing is going to happen now in 2016.

Both 2006 and 2013 were unseasonably warm in early November. This led to heavy rains, which turned the soft snow that usually covers the Russian tundra into hard ice, cutting off the reindeer's food supply of lichen and other vegetation.

"Reindeer are used to sporadic ice cover, and adult males can normally smash through ice around 2 centimeters thick," lead researcher Bruce Forbes from the University of Lapland in Rovaniemi, Finland, shared with New Scientist. "But in 2006 and 2013, the ice was several tens of centimeters thick."

After looking at sea ice and weather records, Forbes and his team found that it all came down to ice coverage in the Barents and Kara seas near the Yamal peninsula. In 2006 and 2013, the ice in these regions began to retreat at the start of November. This is usually the time when the ice would be building up after the summer thaw. That lack of sea ice cover increased evaporation and humidity and combined with unseasonably warm air temperatures, resulting in rain clouds that traveled over the southernmost tip of the Yamal peninsula and poured 24 hours of heavy rain on reindeer herds being moved south for the winter. When the wet ground froze up, it left a layer of thick ice that lasted for months. This kept the reindeer from reaching the vegetation below.

"If we see such events again this year, it could mean that they're becoming more frequent," said Forbes. "Now is the risk window, and if it happens again, it will be a major problem for traditional reindeer herders still suffering from losses in 2013."

With the claims that herds are overgrazing in the northern Russia tundra, a cull of 250,000 reindeer are already expected. With more focused monitoring, researchers are hoping to better predict when this strange ice coverage is going to happen next so the necessary steps to protect wildlife could be made.